Groups of age-matched New Zealand White rabbits will be injected with high, medium, and low concentrations of either streptonigrin or tris(l-aziridinyl)phosphine oxide (TEPA) (two chemicals having known chromosome-breaking activity). After exposure to the compounds for a specific period of time (to be determined from a pilot study) one group of does will be killed, and marrow and blood obtained for cytogenetic study. At the same time, does exposed to identical concentrations of the chemical will be mated to a normal buck. Two other groups of does will be mated 1 and 2 weeks after exposure. All pregnant females will be killed 6 days post-breeding, and blastocysts collected for evaluation of inherited chromosomal abnormalities. From this study we hope to determine: (1) whether compounds that induce chromosome breakages in somatic cells also induce transmissible cytogenetic abnormalities in oocytes, (2) whether the frequencies of aberrations in either lymphocytes or marrow cells can be used to predict the risk of induction of transmissible lesions in female gametes, and (3) whether lymphocytes and marrow cells have different susceptibilities to breakage induction.